Process for oxidizing the side chains of aromatic hydrocarbons.



HARRY D. GIBBS, OF SAN FRANCISCO, CALIFORNIA.

PROCESS FOR- OXIDIZING THE SIDE CHAINS F AROMATIC HYDROCARBONS.

meanest.

No Drawing.

Specification of Letters Patent.

Patented Nov, in, rare.

' Application filed September 22, 1916. Serial No. 121,597.

(DEDICATED TO THE PUBLIC.)

To all whom it may concern:

Be it known that LAHARRY D. Glens, a citizen of the United States of America, and an employee of the Department of Agriculture of the said United States, residing in the city of San Francisco, county of San Francisco, State of California, (Whose post-ofiice address is Department of Agriculture, Washington, D. (1,) have invented a new and useful Process for Oxidizing the Side Chains of Aromatic Hydrocarbons.

This application is made under the act of March 3, 1883, chapter 1&3 (22 Stat, 625), and the invention herein described and claimed may be used by the Government of the United States or any of its officers or employees in the prosecution of work for the Government, or any personin the United States, without payment to me of any royalty.

My invention relates to a process for oxidizing the side chains of aromatic hydrocarbons. My invention constitutes certain steps hereinafter described and specifically set forth in the claims. The following description sets forth in detail certain steps embodying my invention, and such disclosed steps constitute but one of the various ways in which the principle or my invention can be used.

Some of the various methods by which the side chains of aromatic hydrocarbons have been oxidized are as follows:

1. The treatment of liquids, such as toluene and other aromatic hydrocarbons having side chains, with various oxidizing agents, such as manganese dioxid and .sulfuric acid, chromyl chlorid, oxids of cobalt and nickel, with or without sulfuric acid and other oxidizing substances.

2. The exposure of vaporized toluene mixed with air to the influence of catalyzers, consisting of oxids of iron, nickel and copper and carbon (Chasy, Delage and Woog, French Patent No. 379715, July 8, 1907, catalytic process of manufacturing benzaldehyde and benzoic acid).

My invention relates to a method for oxi-- dizing the side chains of aromatic hydrocarbons, the hydrocarbons being first transformed into the gaseous condition and mixed with atmospheric air or oxygen and conducted at various temperatures over catalysts which assist in the union of the oxygen with the side chains of the hydrocarbons. I have discovered that various catalysts can be used for the purpose and have succeeded in producing reactions with platinum and various platinized materials, such as asbestos, oxids of the various metals, aluminum, antimony, bismuth, cerium, chromium, silver, cobalt, magnesium, inolybdenum, tin, titanium, tungsten, uranium, vanadium and zinc, and also various other substances in fine and coarse state of division, such as pieces ,of porcelain, kaolin, and other substances. I have also found that in certain cases mixtures of thesecatalysts produce better results than the catalysts in the pure condition.

The reaction between the hydrocarbons and the oxygen is started by raising the catalyst to a temperature between 200 and OO degrees, centigrade, and then passing the mixture or" the oxygen or atmospheric air or oxygen-containing gas with the hydrocarbons in the gaseous phase over or through the catalyst. In the case of a number of the catalysts mentioned the heat of combustion is sufiicient to maintain the proper temperature for the continuation oi the reaction without the further application of heat. In the case of some of the catalysts above listed it is necessary to concases atmospheric air may be employed.

Many of the catalysts above enumerated are superior to the oxids of iron, nickel andcopper and carbon, which are mentioned in the French Patent No. 379715, July 8 1907, and I have produced yields far in excess of any which it is possible to obtain by these catalysts when I employ the oxids of vanadium, and herein lies the difi'erence and superiority of my process over any other.

In the case of toluene I have found that on mixing the vaporized'hydrocarbon with air or with oxygen, preferably air, and passing the mixture in the gas phase into a chamber containing the catalyst, consist-l ing of oxids of vanadium, raised to a temtigrade, preferably, the reaction proceeds smoothly with the production of benzalde-- products, namely, benzaldehyde and benzoici perature' between 200 and 400 degrees cen hyde and benzoic acid, and there is collected in the receiving vessel a mixture of benzalde- .hyde, *benzoic acid and unchanged toluene and some water. The yields of the valuable acid, are greatly in excess of any yields which have been obtained with other cata lysts and the catalytic action of the oxide of vanadium 'ismuch better than that of the oxide of iron, nickel and copper and carbon, and the process can be continuously operated The toluene may be separated by fractional distillation, mixed with atmospheric airor oxygen and again passed over the catalyst. By proper arrangement of the temperature of the receiving vessel the products of the reaction, benzaldehyde and benzoic acid, condense, while the toluene re-v mains in the form of a gas and is again circulated through the same apparatus or through 'a similar apparatus after it is mixed with the atmospheric air or oxygen.

The products of the reaction, benzaldehydefand benzoic acid, may be separated by a number of gentleman processes, including distillation, separatiortjfcfilthe benzaldeliyde by means of sulfite, 'the removal of benzoic acid as a salt of sodium or of calcium, an other processes.

Having thus-described *iny iinvention, I v

claim: e

1. A process for oxldizing the side chains of aromatic hydrocarbons by. passing the.

gases being maintained at temperatures be- I tween 200 and 4:00 degrees centigrade;

in testimony whereof I afiix my signature in the presence of tWo slibs'cribing witnesses,

HARRY n. GIBBS.

Witnesses:

LAURA A. SKINNER, R. R. WILLIAMS. 

